Light olefins such as ethylene and propylene are important commodity petrochemicals useful in a variety of processes for making plastics and other chemical compounds. Ethylene is used to make various polyethylene plastics, and in making other chemicals such as vinyl chloride, ethylene oxide, ethylbenzene and alcohol. Propylene is used to make various polypropylene plastics, and in making other chemicals such as acrylonitrile and propylene oxide.
The petrochemical industry has known for some time that oxygenates, especially alcohols, are convertible into light olefins. The preferred conversion process is generally referred to as an oxygenate-to-olefin or methanol-to-olefins (both generally referred to as MTO) process, where methanol is converted to primarily ethylene and/or propylene in the presence of a molecular sieve catalyst.
There are numerous technologies available for producing methanol including fermentation or the reaction of synthesis gas (syngas) derived from a hydrocarbon feed stream. Typical feed streams for producing syngas include natural gas, petroleum liquids, coal, recycled plastics, municipal waste, as well as a variety of other organic material.
U.S. Pat. No. 5,714,662 to Vora et al. discloses integrating a methanol synthesis system with an MTO reaction system. This integration involves a combination of reforming, oxygenate production, and oxygenate conversion wherein a crude methanol stream—produced in the production of oxygenates and comprising methanol, light ends, and heavier alcohols—is passed directly to the oxygenate conversion zone for the production of light olefins. Fusel oil in the crude methanol, which typically includes higher alcohols and is generally burned as a fuel in the methanol plant, is passed to the oxygenate conversion process for additional production of light olefins.
U.S. Pat. No. 6,444,712 to Janda et al. discloses a method for the production of methanol and hydrocarbons from a methane-containing gas, such as natural gas. The method integrates a hydrocarbon synthesis unit with a methanol synthesis unit without the need to recycle unreacted syngas exiting the methanol synthesis reactor. A syngas stream and additional carbon dioxide from the hydrocarbon synthesis unit are combined to form an optimal syngas composition for methanol and hydrocarbon synthesis.
It would be desirable to better understand how the integration of various facilities with the MTO process affects product quality. For example, it would be desirable to understand how various oxygenate feeds to the MTO facility affect the quality of a variety of downstream products such as olefins and (co)polymers that are derived from the olefins produced in the MTO process. Accordingly, it would be desirable to establish a method that could be used to track products, particularly MTO products, derived from a particular carbon feed source. In other words, it would be desirable to be able to readily determine from which carbon source a carbon product has been derived.